Fuel filters are currently found in virtually all motor vehicles and are used to clean the fuel before it is fed into a combustion chamber of an internal combustion engine. Such fuel filters often also have a water collection chamber in which water separated from the fuel can be collected and where necessary drained via a corresponding outlet. There is often an active carbon filter downstream of such water collection chambers, which filter is intended to prevent fuel fractions, that is, hydrocarbons, still present in the separated water from reaching the environment in an uncontrolled manner. The disadvantage of such fuel filters is however that at the start of operation fuel first flows through them completely, so that during initial startup the water collection chamber is usually filled with fuel too. If no valve device is provided between the water collection chamber and the upstream active carbon filter, the fuel can come into direct contact with the active carbon in the active carbon filter and saturate it. In these cases an exceptionally high volume of active carbon is necessary to be able to ensure that hydrocarbon fractions are separated out of the separated water during the entire service life of the fuel filter.